SATA JBODs for backup-to-disk

"Steve Cousins" wrote in message
Nik Simpson wrote:
Steve Cousins wrote:
Arno Wagner wrote:

You're going to quote Wikipedia to me as an authorative source?
Well, I can show you a site just as authorative that says differently.

No. I am giving you one reference that explains it and I am telling
you that what is there is the common usage.

I would not say this is "common usage". I've been using JBOD's for
many years and they have mostly had nothing to do with RAID. If you
get an enclosure full of drives it is either a RAID unit or a JBOD.
The only cross-over has been with the 3Ware RAID cards where if you
want to use a drive by itself, not part of a RAID set, then you
specify it as a JBOD drive.

Expansion enclosures for raid storage systems are usually JBOD, they
get their RAID capabilities from the controller in the main enclosure.

So it's a bit too simple to say that JBOD is only used in applications
without RAID.

Or in applications *with* RAID, even.


Sure they can be used in RAID applications. I use them for software RAID
all the time.

But there is nothing about them being JBOD that implies RAID.

Unless they *are* (external) RAID boxes.

That RAID people use JBOD's doesn't mean that the term JBOD implies RAID.

Nor that it doesn't.

"Steve Cousins" wrote in message
Arno Wagner wrote:

You're going to quote Wikipedia to me as an authorative source?
Well, I can show you a site just as authorative that says differently.


No. I am giving you one reference that explains it and I am telling
you that what is there is the common usage.


I would not say this is "common usage". I've been using JBOD's for many
years and they have mostly had nothing to do with RAID.

If you get an enclosure full of drives it is either a RAID unit or a JBOD.

It can be both, depending on whether it has a controller or not.
Controller-less cabinets are often called JBOD cabinets.
One step further it can have a busconverter that converts the internal dri-
ves into the same number of drives with the external bus characteristics.
However, external RAID cabinets can have JBOD as one of the RAID
options and it can be a single volume (multidrive) JBOD as well as multiple
volume (one drive per) JBODs.

The only cross-over has been with the 3Ware RAID cards where if you
want to use a drive by itself, not part of a RAID set, then you specify
it as a JBOD drive.

Actually, that is how it is with almost every RAID controller.
And that is single drive JBOD as opposed to a multidrive JBOD.
Drives still get their own metadata. With some controllers you have to
choose single drive RAID0 or single drive RAID1 to not use stripe or
mirror (=JBOD).


Whether you want to call JBOD (or RAID0 for that matter) a RAID
mode or not, is a matter of taste. The ''R'' is certainly not in them.
But if you relax on the ''R'', then RAID0 and SPAM/APPEND/JBOD
are both RAID modes.


JBOD has no "A" in it either.

Yes it has, in the same sense that there is no "R" in RAID0.
JBOD is an array of 'just a bunch of disks'.

They are not part of an array.

Yes they can be.

No one disk has anything to do with any of the other disks.

Yes they do, in a JBOD array.

That is the whole idea of JBOD's

Nope.
JBOD obviously has no meaning unless you group them in some fashion or
other. Group, array, get it?

(as far as I have ever heard).

Well, there's your problem then.

"Yousuf Khan" wrote in message
Arno Wagner wrote:
Well, then you should adjust your language to the standards that cover
this, unless you want to be misunderstood. JBOD does mean "Just a
Bunch Of Disks", but "Just a Bunch Of Disks" is a RAID mode
also known as SPAN, concat or append mode.

A reference:

http://en.wikipedia.org/wiki/Standard_RAID_levels


You're going to quote Wikipedia to me as an authorative source?

Well, I can show you a site just as authorative that says differently.

Now why don't you.


What is JBOD? - A Word Definition From the Webopedia Computer Dictionary
"Just a Bunch Of Disks Used to refer to hard disks that aren't
configured according to RAID -- a subsystem of disk drives that improves
performance and fault tolerance."

Authorative, huh? Bwahahah.

Still can be an array then, just not one that's "a subsystem of
disk drives that *improves performance and fault tolerance* ".

Try again, idjut.

http://www.webopedia.com/TERM/J/JBOD.html

"Yousuf Khan" wrote in message
Nik Simpson wrote:
Expansion enclosures for raid storage systems are usually JBOD, they get
their RAID capabilities from the controller in the main enclosure. So
it's a bit too simple to say that JBOD is only used in applications
without RAID.


It's very simple,

Ya think?

if you can see and control the disks individually in the OS, then they
are JBODs. If the OS just sees the volume and not the underlying
disks, then it's not JBOD.

Pity single volume-multiple drive JBOD shows up as a single disk.

There are two definitions for JBOD, one for a physical storage cabinet
and one for a logical array type definition, independent of where the
physical drives or the raid controller reside, internal or external.


Yousuf Khan

"Yousuf Khan" wrote in message
Arno Wagner wrote:
Previously Yousuf Khan wrote:
You're going to quote Wikipedia to me as an authorative source? Well, I
can show you a site just as authorative that says differently.

No. I am giving you one reference that explains it and I am telling
you that what is there is the common usage. There is no authorative
siurce as of now, as with a lot other CE/CS terms. But there is common
usage. Vendor brochure usage does not count, vendors will mangle terms
to an arbitrary degree if they think something sounds cool. Just
think of Windows XP. XP means "experimental", period. It has been
meaning that for decades and comes from airplane model designations.
But for MS it means "experience" and they have zero justification
for it.

I worked for a reseller of storage systems for years, and that is the
first time I've ever even heard of JBOD being described as another
term for concatenation.

Right, so obviously you do know better than you let us on to believe here.

To me there was never any confusion about the term, nor any
hint that the term was under confusion, until this discussion.

Except the one that you just created here, troll.


What is JBOD? - A Word Definition From the Webopedia Computer Dictionary
"Just a Bunch Of Disks Used to refer to hard disks that aren't
configured according to RAID -- a subsystem of disk drives that improves
performance and fault tolerance."
http://www.webopedia.com/TERM/J/JBOD.html

Well, that is incomplete but not really add odds with the Wikipedia
definition, now is it? They just stress a bit more that JBOD
does not have redundancy in a bit nebulous way. Whether you want to
call JBOD (or RAID0 for that matter) a RAID mode or not, is a
matter of taste. The ''R'' is certainly not in them. But if
you relax on the ''R'', then RAID0 and SPAM/APPEND/JBOD are
both RAID modes.


Read the discussion forums in the Wikipedia entry about that JBOD term.
It is being described as being completely wrong by most of the
discussees.

I will be editing that definition from Wikipedia in a few
days when I have some time. It's completely wrong.

Like they'll let you, windbag.


Yousuf Khan

"Yousuf Khan" wrote in message
Steve Cousins wrote:
Whether you want to
call JBOD (or RAID0 for that matter) a RAID mode or not, is a
matter of taste. The ''R'' is certainly not in them. But if you relax
on the ''R'', then RAID0 and SPAM/APPEND/JBOD are
both RAID modes.


JBOD has no "A" in it either. They are not part of an array. No one disk
has anything to do with any of the other disks. That is the whole idea
of JBOD's (as far as I have ever heard).


That Wikipedia entry is completely f*ked up, it's time to change it.

It's fine, keep away from it.


Yousuf Khan